On its Web site, Nagoya Body Bath advertises that it's just a few short miles from downtown. Prices range from $40 to $60.

A coupon, featuring a skimpily attired Asian woman, offers 11 percent off for services such as body shampoo and oriental lotion touch.

But authorities say far more was going on behind closed doors than massages and spa treatments at the Mockingbird Lane establishment.

At 7:30 a.m. Wednesday, Dallas police, the district attorney's office and federal agencies raided Nagoya Body Bath and seven other businesses that authorities say were operating as brothels and have possible links to human trafficking.

Some of the spas have been linked to one another, but authorities declined to give further details.

At an afternoon news conference, District Attorney Craig Watkins said he expected to file first-degree felony charges in connection with the investigation.

"We want to make the cost of doing business so high that these folks decide that they don't want to do this business," Mr. Watkins said. "We plan on vigorously prosecuting these individuals. We want to send a message to the community that we're not going to tolerate this in Dallas County."

Twenty-seven women were detained during the raids, and 19 have since been released.

One woman who was detained has been identified as a possible victim of human trafficking. Several women, all South Korean, were being held for immigration reasons.

Police said they were trying to determine if any of the other detainees were human trafficking victims.

Four of the detained women have since been arrested on warrants related to the investigation. Authorities have arrest warrants for nine others.

Police seized cash totaling about $35,665 during the raids.

Wednesday's raids were similar to those carried out in August 2005 on a group of eight Asian spas that resulted in the detention of 42 sex workers. That crackdown was part of an extensive investigation that stretched from brothels in Dallas to Los Angeles and San Francisco.

Three reputed Dallas kingpins went to federal prison last year for their roles in the criminal enterprise that brought South Korean women to town from Seoul, Los Angeles and New York, among other locales.

Those raids generated concerns from victims' advocates critical of the government's handling of the prostitutes' fight for legal protection as human-trafficking victims. In that case, many of the women were working in indentured conditions, servicing up to a dozen customers a day.

But on Wednesday, Bill Bernstein, deputy director of Dallas-based Mosaic Family Services, gave credit to law enforcement agencies for their efforts to identify victims after the morning raids.

"Law enforcement certainly was willing to look at the women who were taken into custody as potential victims," he said. "They went at it with that perspective."

Mosaic, part of the North Texas Anti-Trafficking Team, worked with agencies to help screen victims and offer assistance.

"Determining if someone is truly a victim is very detailed, hard work," Mr. Bernstein said.

Dallas police Deputy Chief Julian Bernal said Wednesday's raids and the earlier stings are part of an ongoing effort to crack down on houses of prostitution. He said authorities would continue to target seven or eight spas at a time for such raids.

"We can only do so many investigations on so many places at one time," Chief Bernal said. "They're very lengthy investigations. They're very time-consuming."

Rather than using a piecemeal strategy of tackling single prostitution cases, authorities are taking a comprehensive approach and involving agencies such as the Internal Revenue Service and Immigration and Customs Enforcement. A main component is ensuring that the business and its assets are seized, as was the case in the 2005 raids.

"As long as there are businesses that are masquerading as legitimate businesses and that are in the business of providing sex acts for money, we're going to target them in this fashion," Chief Bernal said.

To obtain arrest and search warrants, Dallas vice officers gathered evidence of prostitution at the eight businesses that were raided Wednesday.

For example, the price for sexual acts ranged from $100 to $200 at Oasis Body Bath on Mockingbird Lane, according to court records. Between January 2005 and April 16, undercover officers went to the business five separate times and made arrangements to pay for sexual acts.

In a September 2006 interview, a confidential informant who worked at the spa told police that the owner of the business worked as a prostitute along with the other women.